use twitter-stream's reconnect-on-timeout behaviour

twitter-stream ~> 0.1.16 takes care of reconnecting when no data has
been received for a while.  With earthquake also doing this, strange
behaviour occurs when twitter-stream 0.1.16 is used.

Update the dependency to twitter-stream ~> 0.1.16 and remove the
reconnect-on-timeout code from Earthquake::Core to restore normal
behaviour.